Cathode ray storage tube apparatus



July 4, 1967 E. T. WILBUR CATHODE RAY STORAGE TUBE APPARATUS 8 Sheets-Sheet l Filed June l0, 1964 ,NANNWI MSK (ryyayyd/ 774/1/7 MAW/yy July 4, 1967 E. T. WILBUR 3,329,860

CATHODE RAY STORAGE TUBE APPARATUS Filed June lO, 1964 8 Sheets-Sheet 2 mf a rwz a' WW July 4, 1967 E. T. WILBUR CATHODE RAY STORAGE TUBE APPARATUS 8 Sheets-Sheet 5 Filed June lO, 1964 July 4, 1967 Filed June lO, 1964 E. T. WILBUR 3,329,860

CATHODE RAY STORAGE TUBE APPARATUS 8 Sheets-Sheet 4 July 4, 1967 E. T. WILBUR 3,329,860

CATHODE RAY STORAGE TUBE APPARATUS July 4, 1967 E. T. WILBUR CATHODE RAY STORAGE TUBE APPARATUS 8 Sheets-Sheet 6 Filed June l0, 1964 July 4, 1967 E. T. WILBUR CATHODE RAY STORAGE TUBE APPARATUS 8 Sheets-Sheet '7 Filed June lO, 1964 July 4, 1967 E. T. WILBUR CATHODE RAY STORAGE TUBE APPARATUS 8 Sheets-Sheet 8 Filed June lO, 1964 nms@ United States APatent O 3,329,860 CATHODE RAY STORAGE TUBE APPARATUS Everett T. Wilbur, Playa Del Rey, Calif., assignor to Hughes Aircraft Company, Culver City, Calif., a corporation of Delaware Filed June 10, 1964, Ser. No. 373,915 13 Claims. (Cl. 315-24) ABSTRACT OF THE DISCLOSURE The storage target of the disclosed cathode ray storage tube apparatus is scanned by a Write line presenting radar information in either a full PPI pattern, a sector PPI pattern or a B-scan pattern, as well as by an erase line having a predetermined constant parallel relationship with the write line. For the'PPI modes, a scan shifting voltage in quadrature with a scan control voltage is added to an offset voltage indicative of the envelope of the scan control voltage to produce an erase scan deflecting voltage-For the B-scan mode, an offset voltage derived from a selectively inverted ltered sweep voltage is added to a scan control voltage obtained from a linea-r potentiometer.

This invention relates to cathode ray storage tube apparatus and more particularly to such apparatus including an improved voltage generator for developing electron beam scanning voltages.

One problem which has arisen in connection with cathode ray storage tubes is the optimization of the spatial relationship between the loci of pairs of electron beam scan lines. For example, in a cathode ray storage tube of the kind described in U.S. Patents 3,089,055 and 3,089,056 assigned to the instant assignee, wherein scanning electron beams of different predetermined energy levels impinging on a storage target effect the writing and selective erasure of information on a visual display screen by controlling the pattern of electric potential on the target and thus the flow of flood electrons therethrough to the screen, it is desirable to erase just before writing so as to improve resolution, avoiding, however, the twin evils of too much and too little space between the locus of the erase beam scan line and that of the write beam scan line, the former of which would result in undue interruption of access to information, and the latter of which might result in overlapping of the scans and possibly complete loss of the information.

The solution to this problem may take somewhat different forms, depending on the type of impingment pattern desired. Thus, when B-scan presentation with vertically scanning electron beams is utilized, each of the vertical scans being progressively displaced in a horizontal direction to form a rectangular display of range versus azimuth, direct-current bias added to or subtracted from an erase scan horizontal deflection voltage whose envelope otherwise matches that of the write scan horizontal deection voltage is suicient to establish and maintain a predetermined parallel oi'fset between the locus of the erase scan line and that of the write scan line. However, a xed horizontal bias will not yield constant offset parallel tracking between the loci of the erase and write scan lines when PPI types of presentation are utilized, for the offset will then vary between a maximum when the write s'can is vertical and zero when the write scan is horizontal. For the PPI types of presentation a constant angular offset may be provided between the loci of erase and write scan lines, but this results in different Ibackgroundillurriination in the region of the vertex of the scans than in the region of thescan ends most remote 3,329,860 Patented July 4, 1967 ICC to the disadvantage that the erasing may be either too close to the writing at the vertex, possibly even overlapping, or too far from the writing at the end most remote from the vertex, thereby creating too much dead space on the screen.

An object of the present invention therefore is to provide means to improve the resolution of cathode ray storage tubes wherein storage and erase functions may be performed simultaneously.

Another object of the present invention is to provide means for optimizing the spatial relationship between the loci of erase and write beam scanning lines of the storage target of cathode ray storage tubes.

With respect to the preceding object it is also an object of this invention to provide an improved voltage generator capable of furnishing sweep voltages of the type required to accomplish the preceding object.

A further object of the invention is to provide means for developing two moving scan lines whose loci have a predetermined constant parallel relationship on the storage target of a cathode ray storage tube.

Briefly, these and other objects of the invention are achieved in cathode ray storage tube apparatus by providing means for producing a pair of scan lines each of which is progressively displaced by a scan-shifting voltage in a direction orthogonal to the scanning direction,

means for developing a predetermined offset voltage, and summing means coupled to both of the aforementioned means for adding the offset voltage to the scan-shifting voltage, the locus of one of the shifting scan lines being thereby placed substantially parallel to the other with a predetermined offset therebetween.

The above-mentioned and other features of this invention will best be understood from the following description of exemplary embodiments thereof taken in conjunction with the accompanying drawings in which like characters refer to like parts, and wherein:

FIGURE la is a block diagram of one embodiment of the present invention comprising a` cathode ray tube with a storage screen and means for operation thereof in full PPI mode;

FIGURE 1b is a graph of a linear time varying function such as antenna angle versus time for the embodiment of FIGURE la.

FIGURE lc is a diagram of voltage waveform associated with the embodiment of FIGURE la;

FIGURE ld is a diagram ofthe scanning patterns of the write and erase beams resulting from operation of the embodiment of FIGURE la;

FIGURE 2a is a block diagram of another embodiment of the present invention comprising a cathode ray tube with a storage screen and means for operation thereof in sector PPI mode;

FIGURE 2b is a graph of a linear time varying function such as antenna angle versus time for the embodiment of FIGURE 2a;

FIGURE 2c is a diagram of voltage waveforms associated with the embodiment of FIGURE 2a;

FIGURE 2d is a diagram of the scanning patterns of the write and erase beams resulting from operation of the information storage means of FIGURE 2a;

FIGURE 3a is a block diagram of a third embodiment of the present invention comprising a cathode ray tubel with a storage screen and means for operation thereof in B-scan mode;

FIGURE 3b is a graph of a linear time varying function such as antenna angle versus time for the embodifrom the vertex. Constant angular offset is also subject l 3 the Write and erase beams resulting from operation of the embodiment of FIGURE 3a; and

FIGURE 4 is a block diagram of the embodiments of FIGURES 2a and 3a and a Switching arrangement t0 permit operation thereof in B-scan mode and sector PPI mode selectively.

One system for achieving a full PPI presentation with one scan is set forth in the MIT Radiation Laboratory Series, vol. 22, pages 472-473, McGraw-Hill (1948). In any such presentation the distance between the center of the display or storage screen and any point on the locus of a radial scan emanating therefrom, such as the write scan 2 in FIGURE 1d, can be resolved into horizontal and vertical components which respectively satisfy the following equations:

Where Kt) represents the range sweep and is defined from a vertical reference on the screen. Hence, the distance between the center of the display or storage screen and any corresponding point on the locus of another scan, such as the erase scan 4 in FIGURE 1d, which is offset from the locus of the radial scan by a fixed distance and maintains a parallel relationship therewith, can be resolved into horizontal and vertical components which respectively satisfy the following equations:

S1H=f(f) Sin 77 S1v=f(f) COS 17 URE 1a, includes a cathode ray tube 6 comprising write and erase electron beam producing means 8, a storage screen 10, and beam deilectors 12, 14, 16, 18 for vertical and horizontal deflection of write and erase beams. Each deflector may include an amplifier, such as that discussed in the Electronic Designers Handbook, Mc- Graw-Hill (1957), at pages 3-69, and either deflection plates or coils. FIGURE la also shows a radar antenna 20 mounted on a rotatable shaft 22 which is coupled to a drive shaft 24. A radar receiver (not shown), coupled between the antenna 2i) and the beam producing means 8, provides informational input to the latter. An equivalent signal source may of course be utilized in place of the antenna 20 and the radar receiver.

To provide full 360 coverage by the antenna 2f) the shaft drive 24 rotates the shaft 22 continuously in one direction as indicated by the graph of antenna angle versus time in FIGURE lb. Such operation is the basis for the full PPI presentation shown in FIGURE 1d.

To provide the write beam deflectors 12, 14 with voltages for scanning the write beam in a rotating pattern a first sweep generator 26 is provided and a sine-cosine resolver 28, which may be a potentiometer, is mounted on the shaft 22 and electrically coupled to the sweep generator 26. The sweep generator 26 may be of a conventional type, such as that discussed in the MIT Radiation Laboratory Series, vol. 1, pages 510513, McGraw-Hill (1947), and the resolver 28 may also be of a conventional type such as that discussed in the same series, vol. 22, pages 202-204. Referring to FIGURE 1c, a positive waveform 30 and a negative Waveform 32 are shown representing output voltages provided by the sweep generator 26 to energize the resolver 28. As a consequence of such energzation and of mechanical rotation of the shaft 22 the resolver 28 provides a voltage of waveform 34 ha-ving a cosinusoidal envelope to the vertical write beam deilector 12 and a voltage of Waveform 36 having a sinusoidal envelope to the horizontal write beam deflector 14, the deflectors 12, 14 being respectively coupled to the appropriate output terminals of the resolver 28.

To provide voltages for scanning the erase beam a second sweep generator 38 is provided and a second sinecosine resolver 40 is mounted on the shaft 22 and is electrically coupled to the generator 38. FIGURE 1c shows a positive waveform 42 and a negative waveform 44 representing output voltages provided by the second sweep generator 38 to energize the second resolver 40. Thus energized and with the shaft 22 rotating, the resolver 40 provides at different output terminals (not shown) a voltage of waveform 46 having a cosinusoidal envelope and a voltage of waveform 48 having a sinusoidal envelope. Like phasing of each of these envelopes with the corresponding envelope of the voltage waveforms 34, 36 provided by the first resolver 28 is lachieved conventionally by orienting the resolvers 28, 40 similarly with respect to the antenna shaft 22 on which they are mounted.

The horizontal component (VH in FIG. 1d) of the offset between write scan 2 and erase scan 4 is achieved by coupling a first low pass filter 5() to one output terminal of the second resolver 40 to provide an offset voltage of cosinusoidal waveform 54, coupling a first summing network 52 to the low pass filter 50 and to the sinusoidal envelope terminal of the second resolver 40 for adding the cosinusoidal offset voltage of waveform 54 to the sinnsoidally modulated sweep voltage of waveform 48 thereby producing the horizontal erase deflection voltage 56, and coupling the horizontal erase beam deector 18 to the summing network 52. This satsifies Equation 3 above. The low pass filter 50 may be of a conventional type such as that discussed in the Reference Data for Engineers, LT. & T. (1956), page 183. The summing network may likewise be of a conventional type like that discussed in the same publication at page 458.

The vertical component (Vv in FIG. 1d) of the offset between the two scans 2, 4 is achieved by coupling a second low pass filter 58 to the other output terminal of the second resolver 40 to provide an offset voltage of sinusoidal waveform 60, coupling a second summing network 62 to the second low pass filter 58 and to the cosinusoid-al envelope terminal of the second resolver 40 for adding the sinusoidal offset voltage of waveform 60 to the cosinusoidally modulated sweep voltage of waveform 46 thereby producing the vertical erase deflection voltage of Waveform 64, and coupling the vertical erase beam deilector 16 to the second summing network 62. This satisfies Equation 4 above.

It will be appreciated that synchronous detectors may be used in place of the low pass filters 50, 58. It will Ialso be appreciated that linstead of the two sweep generators 26, 38 and the two resolvers 28, 40l a single sweep generator and a single sine-cosine resolver may be used where there is no objection to utilizing identical sweep Voltage frequencies and configurations for write and erase scanning. In the instant embodiment sweep voltages are provided having waveforms 30, 42 whose frequencies and configurations are different from each other to permit more frequent and even erasure before each scan of the write beam.

In accordance with the present invention the means provided for optimizing the spatial relationship between erase and write scanning patterns in a sector PPI presentation, such as that shown in FIGURE 2d, are, with some exceptions, the same as the means described above for doing so in a full PPI presentation. The same equations for the display apply, except that the beginning of the write scan, which is taken as the origin of coordinates, is displaced from the center of the screen, and the antenna angle 1; is limited to less than 180. Since the antenna rot-ates only partially, as shown in the graph of antenna angle versus time (FIGURE 2b), swinging back and forth to cover a predetermined sector, provision must now be made to invert the offset voltage at the end of each autenna sweep, so that the erase scan will reverse direction across the write scan and continue to lead it in much the way that the outer edge of a windshield wiper reverses direction at the end of each stroke and continues to lead the edge in contact with the windshield.

FIGURE 2a, which is a block diagram Showing one implementation of the present invention for developing a sector PPI presentation, is the same as FIGURE 1a with the following exceptions: A cathode ray storage tube, like the tube 6 of FIGURE la, is utilized but not shown. A rotation direction indicator 66 is provided additionally and mounted on the shaft 22, and a relay (comprising a solenoid 68 and first and second movable conductive arms 74, 76) is also provided, the solenoid 68 being electrically coupled to the indicator 66 to respond to its output signals. In FIGURE 2a the first summing network 52 is coupled to the first movable arm 74 rather than directly to the first low pass filter 50, as in FIGURE 1a, and the second summing' network 62 is coupled to the second movable arm 76 rather than directly to the second low pass filter 58. A first inverter 70 and a first inverter by pass conductor 72 are coupled to the first low pass filter 50; and a second inverter 78 and second inverter bypass conductor 80 are coupled to the second low pass filter 58. The inverters 70, 78 may 4be of a conventional type such as that discussed in the Electronic Designers Handbook, McGraw-Hill (1957), pages 3-64. The first movable arm 74 is thus in selective contact with the output terminal of Athe first inverter 70 and, through conductor 72, with the output terminal of the first low pass filter 50, depending on the direction of rotation of the antenna shaft 22. The second movable arm 76 is similarly in selective contact with the output terminal of the second inverter 78 and, through conductor 80, with the output terminal of the second low pass filter 58, depending on the direction of rotation of the antenna shaft 22. Electronic gate circuits may, of course, be utilized instead of the above-mentioned relay.

FIGURE 2c shows the voltage waveshapes associated with the embodiment of the invention shown in FIGURE 2a. Despite the close similarity between this embodiment and that shown in FIGURE la most of the waveshapes provided by corresponding portions of these embodiments are substantially different, primarily because of the periodically reversing partial rotation of the antenna 20 when in sector PPI operation yas compared with the continuous unidirectional rotation of the antenna 20 when in full PPI operation.

Thus, the sweep voltage waveforms 30, 32 provided by the fiirst sweep voltage generator 26 are the same in both embodiments, -but the output voltage waveforms 82, 84 (FIGURE 2c) provided by the first sine-cosine resolver 28 when in sector PPI operation have substantially different envelopes from the corresponding output voltage waveforms 34, 36 (FIGURE lc) of the same resolver 28 when in full PPI operation. The envelope of waveform 82 (FIGURE 2c) appears almost triangular, making a sharp turn at the maximum and minimum points rather than a smooth curve like the complete cosinusoid of the envelope of waveform 34 (FIGURE 1c). However, it is not triangular, but rather a potrion of a cosinusoid, with the angle varying back and forth between, for example, 45 and 135. The envelope of waveform 84 (FIGURE 2c) is a repetitive positive portion of -the complete sinusoid which is the envelope of waveform 36 (FIGURE 1c). 'Ihese differences arise from the limitation of the antenna angle in sector PPI operation as compared with full PPI operation and from the periodic reversal of the rotational direction of the antenna 20 in sector PPI operation. The more severe the limit-ation of antenna angle between reversals of rotational direction, the more pronounced will these differences be.

y Similarly, while the second sweep voltage generator 38 provides voltages whose waveforms 42, 44 are the same in both embodiments, during sector PPI operation the second sine-cosine resolver 40 provides one voltage of waveform 86 whose envelope, being substantially the same as that of waveform 82, differs in the same way from the envelope of waveform 34, and another voltage of waveform 88 whose envelope, being substantially the same as that of waveform 84, differs in the same way from the envelope of waveform 36. Being coupled to the terminal of the second sine-cosine resolver 40 at which the voltage of waveform 88 appears, the first low pass filter 50 is energized thereby to provide a voltage of waveform 90. The first inverter which is coupled to the rst low pass filter 50, inverts the voltage of waveform 90 to provide a voltage of waveform 92. The first movable arm 74 of the relay is actuated by the solenoid 68 in response to signals provided by the rotation direction indicator 66 to selectively provide the portions of voltage waveforms 90, 92 to the first summing network 52 indicated by the offset voltage of wave form 94. Inasmuch as the summing network 52 is coupled to the terminal of the second sine-cosine resolver 40 at which the voltage of waveform 86 appears, the offset voltage of waveform 94 is added thereto to provide the voltage of waveform 96 to the horizontal erase beam deflector 18. The horizontal component of the offset between write scan 2 and erase scan 4 (FIG- URE 2d) is thus achieved as required by Equation 3 above.

The second low pass filter S8, being coupled to the output terminal of the second sine-cosine resolver 40 at which the voltage of waveform 86 appears, is energized thereby to provide a voltage of waveform 98. The second inverter 78, which is coupled to the second low pass filter 58, inverts the voltage of waveform 98 to provide a voltage of waveform 100. The second movable arm 76 of the relay is actuated by the solenoid 68 in response to signals provided by the rotation direction indicator 66 to selectively provide the portions of voltage waveforms 98, 100 to the second summing network 62 indicated by the offset voltage waveform 102. The summing network 62 being coupled to the terminal of the second sine-cosine resolver 40 at which the voltage of waveform 88 appears, the offset voltage of waveform 102 is added thereto to provide the voltage of waveform 104 to the vertical erase beam defiector 16. The vertical component of the offset between write scan 2 and erase scan 4 (FIGURE 2d) is thereby achieved as required by Equation 4 above.

As indicated above, a parallel offset relationship between write and erase scanning patterns in B-scan presentation such as that shown in FIGURE 3d may be achieved by adding a fixed, direct-current bias to an erase beam horizontal deflection voltage, the polarity of the bias changing on signal such as that available from an indicator when the rotational direction of an antenna reverses. A block diagram of an embodiment of the invention to achieve this result is shown in FIGURE 3a which is the same as FIGURE 2a with the following exceptions: The first sine-cosine resolver 28 is not utilized, and the vertical write beam deflector 12 is coupled directly t'o one output terminal of the first sweep generator 26 instead. A linear potentiometer 106 is provided, mounted on the shaft 22 and energized by a direct current voltage source 10S. The horizontal write Vbeam deflector 14 is coupled to an output terminal of the linear potentiometer 106. The second sine-cosine resolver 40 is not utilized, nor are the second low pass filter 58, the second inverter by-pass conductor 80, the second movable relay arm 76, and second summing network 62. Instead of being coupled to the second summing network 62, the vertical erase beam deflector 16 is coupled directly to the second sweep generator 38.

75 The first low pass filter 50 is also coupled to the second sweep generator 38. The first summing network 52 is coupled to the linear potentiometer 106.

FIGURE 3c shows the voltage waveshapes associated with the embodiment of the invention shown in FIGURE 3a. inasmuch as the antenna 20 rotates partially, swinging back and forth as shown in the graph of FIGURE 3b to cover a sector of less than 180, the linear potentiometer 106 provides a corresponding output voltage of waveform 110. An offset voltage of waveform 112 is obtained from the sweep voltage of waveform 42, provided by the second sweep generator 38, by means of the combined operation, described above, of the low pass filter 50, the inverter 52, and the relay comprising the movable arm 74 and the solenoid 68 energized by the rotation direction indicator 66. This offset voltage is added to the output voltage of the linear potentiometer 166 in the summing network 52 to provide a voltage of waveform 114 to the horizontal erase beam deector 18. The vertical erase beam deflection voltage of waveform 30 is provided by the second sweep generator 3S to the detiector 16. FIG- URE 3d shows the resultant scanning pattern at successive times, the vertical scans 2, 4 proceeding in parallel relationship to produce a rectangular pattern of range versus azimuth, the erase scan 4 leading the write scan 2 by a predetermined horizontal offset distance and reversing direction at right and left limits to continue to lead.

FIGURE 4 shows an embodiment of the present invention comprising the embodiment thereof described above and in FIGURE 2a for providing sector PPI presentation, the embodiment thereof described above and in FIGURE 3a for providing B-scan presentation, and a switching arrangement for selecting one or the other.

What is claimed is:

1. Cathode ray storage tube Iapparatus including a storage target capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative Of radial distance along one of two inter secting lines forming a time varying angle, second means for producing an erase ibeam, third means for defiecting said write beam in first and second orthogonal directions, fourth means for defiecting said erase -beam in said directions, and fifth means for providing sweep carrier voltages having first, second, third and fourth waveforms of which the first and third have envelopes which vary in accordance with the sine of said angle and the second land fourth have envelopes which vary in accordance with the cosine thereof, said fifth means being coupled to said third means for applying thereto the sweep carrier voltages of said first and second waveforms to scan said Write beam and thereby form an impingement line across said target in a progressively displaced radial manner corresponding to said angle, comprising:

sixth means coupled to said fifth means for providing a first offsetting voltage proportional to the envelope of said third sweep carrier voltage;

seventh means coupled to said fifth means for providing a second offsetting voltage proportional to the envelope of said fourth sweep carrier voltage;

eighth means coupled between said fourth means and a first combination including said sixth means and said fifth means for providing to said fourth means a first offset deection voltage whose instantaneous value is the sum of said fourth sweep carrier voltage and said first offsetting voltage; and

ninth means coupled between said fourth means and a second combination including said seventh means and said fifth means for providing to said fourth means a second offset deflection voltage whose instantaneous value is the sum of said third sweep carrier voltage and said second offsetting voltage, said first and second offset deflection voltages scanning said erase beam across said target in a progressively displaced manner to form another impingement line having a 8 locus parallel to and at a substantially constant distance from the locus of the write beam impingement l-ine and in a predetermined direction therefrom. 2. Cathode ray storage tube apparatus including a storage target -capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative of radial distance along one of two intersecting lines forming a time varying angle and second means for producing an erase beam, comprising:

third means for providing a first sweep carrier voltage having an envelope which varies in accordance with the sine of said angle and la second sweep carrier voltage having an envelope which varies in accordance with the cosine of said angle; fourth means coupled to said third means for providing a first offsetting voltage proportional to the envelope of said first sweep carrier voltage;

fifth means coupled to said third means for providing a second offsetting voltage proportional to the envelope of said second sweep carrier voltage;

sixth means coupled to said fourth means and to said third means for providing a voltage whose instantaneous value is the sum of said second sweep carrier voltage and said first offsetting voltage;

seventh means coupled to said fth means and to said third means for providing a voltage whose instantaneous value is the sum of said first sweep carrier voltage and said second offsetting voltage;

eighth means coupled to said third means for scanning said write beam to form an impingement line across said target in a progressively displaced radial manner corresponding to said angle; and

ninth means coupled to said sixth and seventh means for scanning said erase beam across said target in a progressively displaced manner to form another in1- pingement line having a locus parallel to and at a substantially constant distance from the locus of the write beam impingement line and in a predetermined direction therefrom.

3. Cathode ray storage tube apparatus including a storage target capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative of radial distance along one of two intersecting lines forming a time varying angle and second means for producing an erase beam, comprising:

third means for providing `a first sweep carrier voltage having an envelope which varies in :accordance with the sine of said angle and a second sweep carrier voltage having lan envelope which varies in accordance with the cosine of said angle;

fourth means for providing a third sweep carrier voltage having an envelope varying in accordance with the sine of said angle and a fourth sweep carrier voltage having an envelope varying in accordance with the cosine of said angle;

fifth means coupled to said fourth means for providing a first offsetting voltage proportional to the envelope of said third sweep carrier voltage;

sixth means coupled to said fourth means for providing a second offsetting voltage proportional to the envelope of said fourth sweep carrier voltage;

seventh means coupled to said fifth means and to said fourth means for providing a voltage whose instantaneous value is the sum of said fourth sweep carrier voltage and said rst offsetting voltage;

eighth means coupled to said sixth means and to said fourth means for providing a voltage whose instantaneous value is the sum of said third sweep carrier voltage and said second offsetting voltage;

ninth means coupled to said 'third means for scanning said write beam to form an impingement line across said target in a progress-ively displaced radial manner corresponding to said angle; and tenth means coupled to said seventh and eighth means for scanning said erase beam across said target in a progressively displaced manner to form -another impingement line having a locus parallel to and at a substantially constant distance from the locus of the write beam impingement line and in a predetermined direction therefrom. 4. Cathode ray storage .tube apparatus including a storage target capable of developing patterns of stored charge and including -a directional antenna mounted on a rotatable shaft for providing information signals representative of radial distance of an object from said antenna in a direction viewed by said antenna, the direction of view and a predetermined direction forming a time varying angle, and -including first means coupled to said antenna for providing a write beam modulated in accordance with said signals and including second means for producing an erase beam, comprising:

third means including a first sine-cosine potentiometer coupled to and energized by a first sweep generator for providing a first sweep carrier voltage having an envelope which varies in accor-dance with the sine of said angle and a second sweep carrier voltage having van envelope which varies in accordance with the cosine of said angle; fourth means including a second sine-cosine potentiometer coupled to and energized by a second sweep genera-tor and mounted on said shaft for providing a third sweep carrier voltage having an envelope varying in accordance with the sine of said angle and a fourth sweep carrier voltage having an envelope varying in -accordance with the cosine of said angle;

fifth means including a first tlow pass filter coupled to said second sine-cosine potentiometer for providing a first offsetting voltage proportional to the envelope of said third sweep carrier voltage; sixth means including a second low pass filter coupled to said second sine-cosine potentiometer for providing a second offsetting voltage proportional to the envelope of said fourth sweep carrier voltage;

seventh means including a first summing network coupled to said first low pass filter and to said second sine-cosine potentiometer for providing a voltage whose instantaneous value is the sum of said fourth sweep carrier voltage and said first offsetting voltage;

eighth means including a second summing network coupled to said second low pass filter and to said second sine-cosine potentiometer for providing a voltage whose instantaneous value is the sum of said third sweep carrier voltage and said second offsetting voltage;

ninth means including horizontal and vertical write beam defiectors coupled to said first sine-cosine potentiometer for scanning said Write beam to form an impingement line across said target in a progressively displaced radial manner corresponding to said angle; and

.tenth means including horizontal and vertical erase beam defiectors respectively coupled to said second and first summing networks for scanning said erase beam across said .target in a progressively displaced manner to form another impingement line having a locus parallel to and at a substantially constant distance Ifrom the locus of the write bea-m impingement line and in a predetermined direction therefrom.

5. Cathode ray storage tube apparatus including a storage target capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative of radial distance along one of two intersecting lines forming a time varying angle whose value changes continuously between predetermined equal posi- .tive and negative ylimits no greater than second means for producing an erase beam, third means for deillecting said write beam in first and second orthogonal directions, fourth means for deflecting said erase beam in said directions, and fth means for providing another signal representative of .the rotational direction of said one of two intersecting lines with respect to the other and sweep carrier voltages having first, second, third and fourth waveforms of which the first and third have envelopes which vary in accordance with the sine of said :angle and the second and fourth have envelopes which vary in accordance with the cosine thereof, said fifth means being coupled to said third means for applying thereto the sweep carrier voltages of said first and second waveforms to scan said write beam and thereby form an impingement line across said target in a progressively displaced radial manner corresponding to said angle, comprising:

sixth means coupled to said fifth means and responsive to said other signal for selectively providing a first offsetting voltage proportional to the envelope of said third sweep carrier voltage and the inverse of said first offsetting voltage;

seven-th means coupled to said fifth means and responsive to said other Asignal for selectively providing a second offsetting voltage proportional to the envelope of said fourth sweep carrier voltage and the inverse of said second offsetting voltage;

eighth means coupled between said fourth means and a first combination including said sixth means and said fifth means for providing to said fourth means a first offset defiection voltage whose instantaneous value is the sum of said fourth sweep carrier voltage and, selectively, said first offsetting voltage and the inverse thereof; and

ninth means coupled between said fourth means and a second combination including said seventh means .and said fifth means lfor providing to said fourth means a second offset deflection voltage whose instantaneous value is the sum of said third sweep carrier voltage and, selectively, said second offsetting voltage and the inverse thereof, said first and second offset deflection voltages scanning said erase beam across said target in a progressively displaced manner to form another impingement line having a locus parallel to and -at a substan-tially constant distance from the locus of the write beam impingement line and in a predetermined direction therefrom dependent on the direction of rotation thereof.

6. Cathode ray storage tube apparatus including a storage target capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative ofy radial distance along one of two intersecting lines forming a time varying angle whose value changes continuously between predetermined equal positive and negative limits no greater than |90| and including second means for producing an erase beam, comprising:

third means for providing a first sweep carrier voltage having an envelope which varies in accordance with the sine of said angle and a second sweep carrier voltage having an envelope which varies in accordance with the cosine of said angle;

fourth means for providing a third sweep carrier voltage having an envelope varying in accordance with the sine of said angle and a fourth sweep carrier voltage having an envelope varying in accordance with the cosine of said angle;

fifth means for providing another signal representative of the rotational direction of said one of two intersecting lines with respect to the other;

sixth means coupled to said fourth means for providing a first offsetting voltage proportional to the envelope of said third sweep carrier voltage; seventh means coupled to said fourth means for providing a second offsetting voltage proportional to the envelope of said fourth sweep carrier voltage;

eighth means coupled to said seventh means for providing the inverse of said second offsetting voltage;

ninth means coupled to said -fifth means and, selectively, to said seventh and eighth means for providing said second offsetting voltage and its inverse in accordance with the rotational direction of said one of two intersecting lines; f

tenth means coupled to said ninth and fourth means for providing a voltage whose instantaneous value is the sum of said third sweep carrier voltage and, selectively, said second offsetting voltage and its inverse; eleventh means coupled to said sixth means for providing the inverse of said first offsetting voltage;

twelfth means coupled to said fifth means and, selectively, to said sixth and eleventh means for providing said first offsetting voltage and its inverse in accordance with the rotational direction of said one of two intersecting lines; thirteenth means coupled to said twelfth and fourth means for providing a voltage whose instantaneous value is the sum of said fourth sweep carrier voltage and, selectively, said first offsetting voltage and its inverse; fourteenth means coupled `to said third means for scanning said write beam to form an impingement line across said target in a progressively displaced radial manner corresponding to said angle; and

fifteenth means coupled to said tenth and thirteenth means for scanning said erase beam across said target in a progressively displaced manner to form another impingement line having a locus parallel to and at substantially constant distance from the locus of the write beam impingement line and in a predetermined direction therefrom.

7. Cathode ray storage tube apparatus including a storage target capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative of radial distance along one of two intersecting lines forming a time varying angle whose value changes continuously between predetermined equal positive and negative limits no greater than l90|, second means for producing an erase beam, third means for deflecting said write beam in first and second orthogonal directions, fourth means for defiecting said erase beam in said directions, and fifth means for providing another signal representative of 4the rotational direction of said one of two intersecting lines with respect to the other, first and second sweep carrier voltages, and an additional signal representative of the instantaneous value of said angle, said fifth means being coupled to said third means for applying said first sweep carrier voltage and said additional signal to scan said write beam thereby forming an impingement line in one of said directions across said target and progressively displacing said line in the other of said directions in a manner corresponding to said angle, comprising:

sixth means coupled to said fifth means and responsive to said second sweep carrier voltage and said other signal for selectively providing an offsetting voltage and the inverse thereof depending on the rotational direction of said one of two intersecting lines with respect to the other, said offsetting voltage being proportional to the envelope of said second sweep carrier Voltage; and

seventh means coupled between said fourth means and a combination including said sixth means and said fifth means for providing to said fourth means an offset deflection voltage whose instantaneous value is the sum of said additional signal and, selectively, said offsetting voltage and its inverse, said fifth means being coupled to said fourth means for applying said second sweep carrier voltage thereto to scan said erase beam in said one direction across said target and said offset deflection voltage progressively displacing said scanning beam in said other direction in a manner to form another impingement line having a locus parallel to and at a substantially constant distance from the locus of the write beam impingement line and in a predetermined direction therefrom dependent on the direction of rotation of said one line with respect to the other.

8. Cathode ray storage tube apparatus including a storage target capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative of radial distance along one of two intersecting lines forming a time varying angle whose value changes continuously between predetermined equal positive and negative limits no greater than and including second means for producing an erase beam, comprising:

third means for providing a first sweep carrier voltage of constant peak amplitude;

fourth means for providing a second sweep carrier Voltage of the same peak amplitude;

fth means for providing another signal representative of the rotational direction of said one of two intersecting lines with respect to the other;

sixth means for providing an additional voltage whose waveform is representative of the instantaneous value of said angle; seventh means coupled to said fourth means for providing an offsetting voltage proportional to the peak amplitude of said second sweep carrier voltage;

eighth means coupled to said seventh means for providing the inverse of said offsetting Voltage;

ninth means coupled to said fifth means and, selectively, to said seventh and eighth means for providing said offsetting voltage and its inverse in accordance with the rotational direction of said one of two intersecting lines;

tenth means coupled to said ninth and sixth means for providing yan offset voltage whose instantaneous value is the sum of said additional Voltage and, selectively, said offsetting voltage and its inverse;

eleventh means coupled to said third and sixth means for scanning said write beam to form an irnpingement line across said target progressively displaced in a direction orthogonal to said line, the orthogonal displacement corresponding to said angle; and twelfth means coupled to said tenth and fourth means for scanning said erase beam across said target in a progressively displaced manner to form another impingement line having la locus parallel to and at substantially constant distance from the locus of the write beam impingement line and in a predetermined ydirection therefrom dependent on the rotational direction of said one line with respect to the other.

9. Cathode ray storage tube apparatus including a storage target capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative of radial distance along one of two intersecting lines forming a time varying angle, second means for producing an erase beam, third means for deecting said write beam in first and second orthogonal directions, fourth means for defiecting said erase ,beam in said directions, -and fifth means for providing first :and second sweep carrier voltages respectively having first and second waveforms of which the first has an envelope which varies in accordance with the sine of said angle .and the second has an envelope which varies in accordance with the cosine thereof, said fifth means being coupled to said third means for applying thereto said first and second sweep carrier voltages to scan said Write beam and thereby form an impingement line across said target in a progressively displaced radial manner corresponding to said angle, comprising:

sixth means coupled to said fifth means for providing a first offsetting voltage proportional to the envelope of said first sweep carrier voltage; seventh means coupled to said fifth means for providing a second offsetting voltage proportional to the envelope of said second sweep carrier voltage; eighth means coupled between said fourth means and a first combination including said sixth means and said fifth means for providing to said fourth means a first offset deflection voltage whose instantaneous value is the sum of said second sweep carrier voltage and said first offsetting voltage; and ninth means coupled between said fourth means and a second combination including said seventh means and said fifth means for providing to said fourth means a second offset deflection voltage whose instantaneous value is the sum of said first sweep carrier voltage and said second offsetting voltage, said first and second offset defiection voltages scanning said erase beam across said target in a progressively displaced manner to form another impingement line having a locus parallel to and at a substantially constant distance from the locus of the write beam impingement line and in a predetermined direction therefrom.

10. In a cathode ray storage tube apparatus including a storage target capable of developing patterns of stored charge and including first means for producing a write beam modulated in accordance with information signals representative of radial distance along one of two intersecting lines forming a time varying angle, se-cond means for producing an erase beam, third means for defiecting said write beam in first and second orthogonal directions, fourth means for defiecting said erase beam in said directions, and fifth means for providing first and second sweep carrier voltages respectively having first and second waveforms of which the first has an envelope which varies in accordance With the sine of said angle an-d the second has an envelope which varies in acc-ordance with the cosine thereof, said fifth means being coupled to said third means for applying thereto said first and second sweep carrier voltages to scan said write beam and thereby form an impingement line across said target in a progressively displaced radial manner corresponding to said angle, a voltage generator comprising:

sixth means coupled to said fifth means for providing a first offsetting voltage proportional to the envelope of said first sweep carrier voltage; seventh means lcoupled to said fifth means for providing a second offsetting voltage proportional to the envelope of said second sweep carrier voltage; eighth means coupled between said fourth means and a first combination including said sixth means and said fifth means for providing 4to said fourth means a first offset deflection voltage Whose instantaneous value is the sum of said second sweep carrier voltage and said first offsetting voltage; and ninth means coupled between said fourth means and a second combination including said 4seventh means and said fifth means for providing to said fourth means a second offset deflection voltage whose instantaneous val-ue is the sum of said first sweep carrier voltage and said second offsetting voltage, said first and second offset deflection voltages scanning said erase beam across said target in la progressively displaced manner to form another impingement line having a locus parallel to and at a substantially constant distance from the locus of the Write beam impingement line Iand in a predetermined direction therefrom. 11. A voltage generator comprising: first means for receiving a signal voltage; second means coupled to said first means and responsive to an unmodulated sweep carrier signal voltage for providing first and second modulated sweep carrier voltages returning to a predetermined reference level before each successive sweep thereof and having enevelopes respectively repersentative of equal amplitude sine and cosine functions of an angle continuously varying with time between predetermined limits for further providing a first offset sweep carrier voltage representative of the algebraic sum of a first offsetting voltage proportional to the envelope of said second modulated sweep carrier voltage and a sweep carrier voltage having an envelope and la reference level substantially identical to said first modulated sweep carrier voltage, and for still further providing a second offset sweep carrier voltage representative of the algebraic sum of a second offsetting voltage proportional to the envelope of said first modulated sweep carrier voltage and a sweep carrier voltage having an envelope and a reference level substantially identical to said second modulated sweep carrier voltage; and

third means coupled to said second means for applying said first and second modulated sweep carrier voltages and said offset sweep carrier voltages to a utilization device.

12. A voltage generator comprising:

first means for receiving a signal voltage;

second means coupled to said first means and responsive to an unmodulated sweep carrier signal voltage for providing first and second modulated sweep carrier voltages returning to a predetermined reference level before each successive sweep thereof and having envelopes respectively representative of equal amplitude sine and cosine functions of an angle continuously varying with time between predetermined limits;

third means coupled to said second means for providing a first offset sweep carrier voltage representative of the algebraic sum of a first offsetting voltage proportional to the envelope of said second modulated sweep carrier voltage and a sweep carrier voltage having an envelope and a reference level substantially identical to said first modulated sweep carrier voltage, and for further providing a second offset sweep carrier voltage representative of the algebraic sum of a second offsetting voltage proportional to the envelope of said first modulated sweep carrier voltage and a sweep carrier voltage having lan envelope and a reference level substantially identical to said second modulated sweep carrier voltage; and

fourth means coupled to said second and third means for applying said first and second modulated sweep carrier voltages and said offset sweep carrier voltages to a utilization device.

13. A voltage generator comprising:

first means for receiving two signal voltages;

second means coupled to said first means and responsive to a first unmodulated sweep carrier signal voltage for providing first and second modulated sweep carrier voltages returning to a predetermined reference level before each successive sweep thereof and having envelopes respectively representative of equal amplitude sine and cosine functions of an angle continuously varying with time between predetermined limits;

third means coupled to said first means and responsive to a second unmodulated sweep carrier signal voltage of substantially equal amplitude as said first unmodulated sweep carrier signal voltage for providing third and fourth modulated sweep carrier voltages returning to a predetermined reference level before each successive sweep thereof and having envelopes rspectively bearing the same relationship to each other as the envelopes of said first and second moduaeaaaeo 15 16 lated sweep carrier voltages respectively, the envoltage proportional to the envelope of said first velopes of said rst and third modulated sweep carrier modulated sweep carrier voltage and said second voltages being substantially in phase and of equal sweep carrier voltage; and amplitude, and the envelopes of Said second and fth means coupled to said second and third means fourth modulated sweep carrier voltages being sub- 5 for dPPlB/mg Sald fst'ald Second modulfded SWeeP Stantiauy in phase and of equal amplitude; carrier voltages and said offset sweep carrier voltages fourth means coupled to said second means and reto authzatlon devlce' sponsive to said rst and second modulated sweep carrier voltages for providing a rst offset sweep carrier voltage representative of the algebraic sum of 10 UNITED STATES PATENTS a rst offset-ting voltage proportional to the envelope 2,718,609 9/ 1955 Covely 315--12 X of said second modulated sweep carrier voltage and h c said first sweep carrier voltage, and for further pro- JOHN W' CALDWELL Actmg Pnmary Exammer viding a second offset sweep carrier voltage repre- 15 T. A. GALLAGHER, R. K. ECKERT, JR.

sentative of the algebraic sum of a second offsetting Assistant Examiners.

References Cited 

1. CATHODE RAY STORAGE TUBE APPARATUS INCLUDING A STORAGE TARGET CAPABLE OF DEVELOPING PATTERNS OF STORED CHARGE AND INCLUDING FIRST MEANS FOR PRODUCING A WRITE BEAM MODULATED IN ACCORDANCE WITH INFORMATION SIGNALS REPRESENTATIVE OF RADIAL DISTANCE ALONG ONE OF TWO INTERSECTING LINES FORMING A TIME VARYING ANGLE, SECOND MEANS FOR PRODUCING AN ERASE BEAM, THIRD MEANS FOR DEFLECTING SAID WRITE BEAM IN FIRST AND SECOND ORTHOGONAL DIRECTIONS, FOURTH MEANS FOR DEFLECTING SAID ERASE BEAM IN SAID DIRECTIONS, AND FIFTH MEANS FOR PROVIDING SWEEP CARRIER VOLTAGES HAVING FIRST, SECOND, THIRD AND FOURTH WAVEFORMS OF WHICH THE FIRST AND THIRD HAVE ENVELOPES WHICH VARY IN ACCORDANCE WITH THE SINE OF SAID ANGLE AND THE SECOND AND FOURTH HAVE ENVELOPES WHICH VARY IN ACCORDANCE WITH THE COSINE THEREOF, SAID FIFTH MEANS BEING COUPLED TO SAID THIRD MEANS FOR APPLYING THERETO THE SWEEP CARRIER VOLTAGES OF SAID FIRST AND SECOND WAVEFORMS TO SCAN SAID WRITE BEAM AND THEREBY FORM AN IMPINGEMENT LINE ACROSS SAID TARGET IN A PROGRESSIVELY DISPLACED RADIAL MANNER CORRESPONDING TO SAID ANGLE, COMPRISING: SIXTH MEAND COUPLED TO SAID FIFTH MEANS FOR PROVIDING A FIRST OFFSETTING VOLTAGE PROPORTIONAL TO THE ENVELOPE OF SAID THIRD SWEEP CARRIER VOLTAGE; SEVENTH MEANS COUPLED TO SAID FIFTH MEANS FOR PROVIDING A SECOND OFFSETTING VOLTAGE PROPORTIONAL TO THE ENVELOPE OF SAID FOURTH SWEEP CARRIER VOLTAGE; EIGHTH MEANS COUPLED BETWEEN SAID FOURTH MEANS AND A FIRST COMBINATION INCLUDING SAID SIXTH MEANS AND SAID FIFTH MEANS FOR PROVIDING TO SAID FOURTH MEANS A FIRST OFFSET DEFLECTION VOLTAGE WHOSE INSTANTANEOUS VALUE IS THE SUM OF SAID FOURTH SWEEP CARRIER VOLTAGE AND SAID FIRST OFFSETTING VOLTAGE; AND NINTH MEANS COUPLED BETWEEN SAID FOURTH MEANS AND A SECOND COMBINATION INCLUDING SAID SEVENTH MEANS AND SAID FIFTH MEANS FOR PROVIDING TO SAID FOURTH MEANS A SECOND OFFSET DEFLECTION VOLTAGE WHOSE INSTANTANEOUS VALUE IS THE SUM OF SAID THIRD SWEEP CARRIER VOLTAGE AND SAID SECOND OFFSETTING VOLTAGE, SAID FIRST AND SECOND OFFSET DEFLECTION VOLTAGES SCANNING SAID ERASE BEAM ACROSS SAID TARGET IN A PROGRESSIVELY DISPLACED MANNER TO FORM ANOTHER IMPINGEMENT LINE HAVING A LOCUS PARALLEL TO AND AT A SUBSTANTIALLY CONSTANT DISTANCE FROM THE LOCUS OF THE WRITE BEAM IMPINGEMENT LINE AND IN A PREDETERMINED DIRECTION THEREFROM. 